Machine for converting wooden pieces into chips

ABSTRACT

A machine for converting wooden pieces, such as those formed by a chopping procedure, into chips to be used in chip and particle boards, comprises cutting tools disposed in annular spaces through which the wooden pieces are fed radially outwards and which taper in that direction.

1451 Sept. 18, 1973 111mm States atent 1191 Landmark et al.

241/46 B 241/260 X Hommel 144/180 [54] MACHINE FOR CONVERTING WOODEN 2,973,910 3/1961 Federigni et a1. PIECES INTO CHIPS 2,738,931 3/1956 Schneider............

1,799,814 4/1931 [75] Inventors: Lars-Erik Lundmark, Taby; Evald Larsson, Nassjo, both of Sweden [73] Assignee: AB Krima Maskinfabrik, Nassjo, 'f Exami','er Andrew Juhasz Sweden Ass/stunt Exammer-W. D. Bray Attorney-Flynn & Frishauf [22] Filed: Mar. 17, 1972 ABSTRACT [21] Appl. No.: 235,648

00 6m 2 B12 1 .3 2m M WM Mme 8 "41 a 0 W0 l WW6 mm fim ur/ 4 "e4 S m I C h .1 hF 11 8 55 11.

References Cited UNITED STATES PATENTS 3,101,756 8/1963 Schubert......................... 144/180 X 10 Claims, 3 Drawing Figures PATENIED SEPI 8 I973 PATENTED SEPI 81973 SHEET- 2 OF 2 Fig. 3

MACHINE FOR CONVERTING WOODEN PIECES INTO CHIPS BACKGROUND OF THE INVENTION For the manufacture of chip and particle boards, now increasingly used in the construction industry, it is common to produce wooden chips by division of larger pieces formed by a chopping procedure. That division is generally carried out in a machine comprising a number of cutting tools, shaped like knives mounted on a substantially annular or disk-formed part of the machine and cooperating with means generating a counter-pressure and supported by another part of the machine, the two parts being rotatable relative to each other.

One basic problem in the operation of machines as above set out has been that of avoiding substantial variation in the sizes of the chips, or splinters, produced. Another difficulty stems from the lack of control of the relative positions in which the wooden workpieces are presented to the knives. In consequence thereof the workpieces have been out both in the longitudinal direction of the wooden fibres as well as parallel thereto which has in turn resulted in inferior qualities of the finalized chip and particle boards or similar products.

One object of the present invention is to provide a machine in which the disadvantages and limitations above referred to have been eliminated so that the machine renders itself for manufacture of chips exhibiting a constant and conveniently controllable thickness, the fibres of the wood also being oriented as desired.

A further object of the invention is to provide a machine as described above designed in such a way so that its tools, the cutting knives, get a long useful life and can easily be replaced.

DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION One preferred embodiment of the invention will now be described in greater detail, reference being made to the accompanying drawing, in which:

FIG. 1 is a part-sectional perspective view illustrating 'the main components of a machine designed in accordance with the teachings of this invention;

FIG. 2 shows on a greater scale a perspective view of a portion of the cutting ch'amberof the machine; and

FIG. 3 is a section taken along line III-III in FIG. 2 and illustrating the operation of the cutting tools and the means generating the counter-pressure.

The machine illustrated comprises a stator generally designated and being of cylindrical form. It comprises an upper stator half 11 and a lower stator half 12. Inside the stator there is a rotor disc 13 mounted at the top end of a shaft 14. The latter passes through a shaft housing I5 and a bearing box with a mounting plate 16. At its lower end shaft 14 carries a pulley 17 forming part of a V-belt transmission not shown on the drawing and comprising in the conventional way an electric motor or the like.

The top stator half 11 has a relatively large inlet 18 centrally located in the axial direction of the machine. As is understood, the wooden workpieces, generally formed by a chopping procedure, are fed into inlet 18 in a way which will be described more closely below. Numeral l9 refers to the space defined between rotor disc 13 and the bottom stator half 12. That space forms the working chamber of the machine. The chips produced leave the machine through a radially directed outlet 20. v

The design of the working chamber of the machine is best apparent from FIGS. 2 and 3. Taken together with FIG. 1 those figures show that the working chamber is made up by a plurality of similar spaces separated from each other by a number of substantially radial partitions 21. According to the embodiment of the invention here illustrated those partitions aresecured to the top stator half 11. From there they extend downwardly and their bottom sides have a small clearance from the upper side of rotor disc 13 see FIG. 3. Reference numeral 22 designates a number of cutting knives mounted in the rotor disc for the purpose of severing chips 24 from the workpieces 23 which in this case are generally parallelepipedic or block-shaped wooden pieces formed by a chopping procedure in a manner known per se. After having been peeled of from the workpieces, chips 24 pass through extended slots 25 in the rotor disc. As is best seen from FIG. 3, at each such slot 25 which is of substantially triangular cross-section there is at the one side wall mounted a knife 22 and, at the opposite side wall, a ruler 26 the position of which may be varied for adjustment of the thickness of the chips 24 produced. On top of rotor disc 13 there is a hub dome 27 the upper surface of which has a number of ribs 28 extending in a generally radial direction. Numeral 29 referes to fan wings secured to the lower side of the rotor disc for the purpose of facilitating the passage of chips 24 through outlet 20.

The operation of the machine above described is as follows.

As has already been indicated, the starting material in the form of wooden block workpieces 23 are supplied through inlet 18 as marked by the top arrow in FIG. 1. When the machine is in operation and the rotor rotates ribs 28 on hub dome 27 will, due to the centrifugal force, feed the workpieces into the cutting chamber. As was also mentioned above, each compartment in the chamber is laterally defined by partitions 21 and vertically by rotor disc 13 and the upper stator half 11. From FIG. 2 it is evident that the effective height of-the cutting chamber decreases successively radially outwards and also that the maximum height has been selected in such a way relative to the dimensions of the workpieces that the latter are impeded from assuming an upright position. If they could be presented in such a position, the result would be a cutting of them transverse to the direction of the fibres However, thanks to the described arrangement they will instead be presented in two or more superimposed layers. The work-v pieces in the lowermost layer are successively cut from below by knives 22, which'has been illustrated in FIG. 3. When the height of a workpiece subjected to such a cutting operation is successively decreased the workpiece will, mainly under the influence of the centrifugal force, be displaced radially outwards until it is by a squeezing action exerted between the bottom and top of the cutting chamber again brought into such a position that a second chip is severed from below. This procedure is repeated until all workpieces have been cut. As is understood, in the operation of the machine the entire layers of workpieces will successively move radially outwards, whereas chips 24 leave the machine axially downwards passing through slots 25 and fed on by fan wings 29. It is preferred to limit the maximum axial extension of the cutting chamber to a value less than the maximum dimension of the workpieces to be supplied to the machine, meaning that the workpieces can only assume positions in which they are cut in planes parallel to the fibres. At its outermost radial distance from shaft 14 the cutting chamber has a very limited effective height, basically equal to the double thickness of the chips produced.

It should be emphasized that the invention is primarily based on the realization that the disadvantages and shortcomings of the prior art machines can be avoided thanks to the special design and arrangement of the cutting chamber. From what has been said above it is also apparent that the workpieces are positively fed into the machine. This feeding can take place by means of purely mechanical devices such as stokers, but it is also possible in addition thereto or, as an alternate, to have a superatmospheric steam pressure inside the machine. This has the extra advantage of preheating the wood thus facilitating the cutting operation and increasing the useful life of knives 22. In that case the knives can be made so thin that their manufacturing costs do not warrant re-grinding. Instead, worn out knives are dismissed upon each tool exchange. Partitions 21, the function of which is to set up a counterpressure necessary for the cutting operation of the knives, are preferably of rectangular profile as illustrated in FIG. 3 and provided with sharp corner edges avoiding the risk of stagnation of the workpieces following a squeezing or wedging action. A further advantage of this contour is that each of the partitions can be successively rotated through 90 around its longitudinal axis and, accordingly, used in four different mounting positions. As is realized, this is also advantageous from the standpoint of operational costs. It should also be underlined that in each individual application of the invention rotor shaft 14 may be disposed to suit the actual conditions, above all to match the device supplying the starting material into the machine. It is thus obvious that shaft 14 does not have to be vertical but can also be inclined or horizontal. Finally, it is also feasible to interchange on the one hand the positions of partitions 21 and, on the other hand, knives 22 and rulers 26, so that the partitions are instead supported by the rotor and vice versa.

What is claimed is:

l. A machine for converting wooden workpieces, into chips for use in chip and particle boards and similar products, comprising a plurality of cutting knives supported by a first part of the machine, means for generating a counter-pressure mounted on a second part of the machine, said first and second parts being rotatable relative to each other, said cutting knives and counterpressure-generating means being disposed in compartments the effective height of which successively decreases in the direction radially outwards from a central drive shaft, the workpieces passing through the compartments in said direction while being subjected to the cutting operation.

2. A machine as defined in claim 1, in which the maximum effective height of the compartments is less than the maximum dimension of any individual workpiece.

3. A machine for converting wooden workpieces, into chips for use in chip and particle boards and similar products, comprising a plurality of cutting knives supported by a first part of the machine, means for generating a counter-pressure mounted on a second part of the machine, said first and second parts being rotatable relative to each other, said cutting knives and counterpressure-generating means being disposedin compartments the effective height of which successively decreases in the direction radially outwards from a central drive shaft, the workpieces passing through the compartments in said direction while being subjected to the cutting operation and leave the compartments in a direction parallel to the shaft through slots in one of said two parts.

4. A machine for converting wooden workpieces, into chips for use in chip and particle boards and similar products, comprising a plurality of cutting knives supported by a first part of the machine, means for generating a counter-pressure mounted on a second part of the machine, said first and second parts being rotatable relative to each other, said cutting knives and counterpressure-generating means being disposed in compartments the effective height of which successively decreases in the direction radially outwards from a central drive shaft, the workpieces passing through the compartments in said direction while being subjected to the cutting operation, and means being provided to exert a permanent positive pressure on the workpieces.

5. A machine as claimed in claim 1 wherein said first I part forming a rotor has a hub portion provided with rib-like projections for promoting the supply of wooden workpieces into a tubular inlet centrally disposed opposite said hub portion.

6. A machine as claimed in claim 3 wherein said first part forming a rotor has a hub portion provided with rib-like projections for promoting the supply of wooden workpieces into a tubular inlet centrally disposed opposite said hub portion.

7. A machine as claimed in claim 4 wherein said first part forming a rotor has a hub portion provided with rib-like projections for promoting the supply of wooden workpieces into a tubular inlet centrally disposed opposite said hub portion.

8. A machine as claimed in claim 1 wherein said wooden workpieces are formed by a chopping process.

9. A machine as claimed in claim 3 wherein said wooden workpieces are formed by a chopping process.

10. A machine as claimed in claim 4 wherein said wooden workpieces are formed by a chopping process. i i II 

1. A machine for converting wooden workpieces, into chips for use in chip and particle boards and similar products, comprising a plurality of cutting knives supported by a first part of the machine, means for generating a counter-pressure mounted on a second part of the machine, said first and second parts being rotatable relative to each other, said cutting knives and counter-pressure-generating means being disposed in compartments the effective height of which successively decreases in the direction radially outwards from a central drive shaft, the workpieces passing through the compartments in said direction while being subjected to the cutting operation.
 2. A machine as defined in claim 1, in which the maximum effective height of the compartments is less than the maximum dimension of any individual workpiece.
 3. A machine for converting wooden workpieces, into chips for use in chip and particle boards and similar products, comprising a plurality of cutting knives supported by a first part of the machine, means for generating a counter-pressure mounted on a second part of the machine, said first and second parts being rotatable relative to each other, said cutting knives and counter-pressure-generating means being disposed in compartments the effective height of which successively decreases in the direction radially outwards from a central drive shaft, the workpieces passing through the compartments in said direction while being subjected to the cutting operation and leave the compartments in a direction parallel to the shaft through slots in one of said two parts.
 4. A machine for converting wooden workpieces, into chips for use in chip and particle boards and similar products, comprising a plurality of cutting knives supported by a first part of the machine, means for generating a counter-pressure mounted on a second part of the machine, said first and second parts being rotatable relative to each other, said cutting knives and counter-pressure-generating means beinG disposed in compartments the effective height of which successively decreases in the direction radially outwards from a central drive shaft, the workpieces passing through the compartments in said direction while being subjected to the cutting operation, and means being provided to exert a permanent positive pressure on the workpieces.
 5. A machine as claimed in claim 1 wherein said first part forming a rotor has a hub portion provided with rib-like projections for promoting the supply of wooden workpieces into a tubular inlet centrally disposed opposite said hub portion.
 6. A machine as claimed in claim 3 wherein said first part forming a rotor has a hub portion provided with rib-like projections for promoting the supply of wooden workpieces into a tubular inlet centrally disposed opposite said hub portion.
 7. A machine as claimed in claim 4 wherein said first part forming a rotor has a hub portion provided with rib-like projections for promoting the supply of wooden workpieces into a tubular inlet centrally disposed opposite said hub portion.
 8. A machine as claimed in claim 1 wherein said wooden workpieces are formed by a chopping process.
 9. A machine as claimed in claim 3 wherein said wooden workpieces are formed by a chopping process.
 10. A machine as claimed in claim 4 wherein said wooden workpieces are formed by a chopping process. 